Hi! The windows GDI driver has a bug which triggers an assertation in src/mesa/main/ renderbuffer.c, line 1628 (assert(fb->Attachment[b].Renderbuffer);) when it is told to setup a double buffered context with alpha planes. This happens because it creates the BUFFER_FRONT_LEFT only in for single-buffer, and only BUFFER_BACK_LEFT for double-buffer. I attached a proposed fix (which also fixes 2 unrelated warnings), but am not sure the fixes are correct because the same renderbuffer is used for front and back. However the GDI driver seems to use a single memory bitmap if double buffering is enabled, which it bitblts into the window when the buffers are swapped so the changes should be ok I think.
Created attachment 3706 [details] [review] GDI driver doublebuffer+alpha proposed fix
Created attachment 3707 [details] [review] renderbuffer patch for wmesa.c I've taken a stab at writing the right code, but can't test it. I'm attaching the diff for you to try.
Gregor Anich, Do you still experience this issue with newer soft? Please check the status of your issue.
The windows GDI driver has since been removed from Mesa.
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